Originally from Argentina, Agar moved to London in 1906 where she studied at the Slade School of Fine Art between 1925 and 1926. From 1928 to 1930, she studied in Paris and became member of the London Group in 1933. Her works were selected by Roland Penrose and Herbert Read for the International Exhibition of Surrealism held at the New Burlington Galleries, London in 1936. Agar exhibited with the Surrealist group on a regular basis both in Britain and abroad. In 1936, she began experimenting with other techniques and new materials such as photography and collage. In the 60s, she concentrated on "tachist" paintings with surrealist features.